What is the length of the line segment from the point (2, -1, 1) to the point (4, -4, 7) ?
What is the angle at the point (0, 1, -1) in the triangle whose vertices are that point, the point (-1, 3, 1), and the point (3, 7, -3) ?
Let M be the 2 \times 3 matrix
M = |
| , |
Find a basis consisting of mutually perpendicular vectors for the plane in R^{3} defined by the linear equation
2 x - y + 2 z = 0 . |